Organic materials have been investigated for use as the semiconductor layers in thin film field effect transistors (xe2x80x9cFETsxe2x80x9d). Organic materials are attractive because they are easily processable and are compatible with the plastic substrates on which thin film FETs can be formed. Such advantages are important when fabricating low cost, large area devices. The conventional approach to forming the organic semiconductor layer is to employ a solution where the organic material is dissolved in a solvent. The semiconductor layer is then formed by coating the solution of the organic material followed by evaporating off the solvent. Using a solution based approach where an organic material is soluble in a solvent, however, limits the choice of organic materials for the semiconductor layer. Thus, there is a need which the present invention addresses for new techniques to form organic semiconductor layers to expand the choice of organic materials that can be used in the semiconductor layers.
The following documents may be relevant to the present invention:
Bao et al., U.S. Pat. No. 6,107,117;
Katz et al., U.S. Pat. No. 6,252,245 B1;
Dimitrakopoulos et al., U.S. Pat. No. 5,946,551;
Keoshkerian et. al. U.S. Pat. No. 5,482,811;
Keoshkerian et. al. U.S. Pat. No. 5,563,261;
Murti et. al. U.S. Pat. No. 6,319,645 B1;
Zhenan Bao, xe2x80x9cMaterials and Fabrication Needs for Low-Cost Organic Transistor Circuitsxe2x80x9d Adv. Mater. Vol. 12, No. 3, pp. 227-230 (2000); and
C. D. Dimitrakopoulos et al., xe2x80x9cOrganic thin-film transistors: A review of recent advancesxe2x80x9d IBM J. RES. and DEV. Vol. 45, No. 1, pp. 11-27 (January 2001).
The present invention is accomplished in embodiments by providing a process comprising:
creating a dispersion including: (a) a continuous phase comprising a solvent, a binder resin at least substantially dissolved in the solvent, and (b) a disperse phase comprising an organic semiconductor material; and
solution coating using the dispersion to form a semiconductor layer of an electronic device, wherein the semiconductor layer comprises the organic semiconductor material and the binder resin.
In further embodiments of the present invention, there is a process for fabricating a field effect transistor comprising:
forming an insulating layer, a gate electrode, a semiconductor layer, a source electrode, and a drain electrode,
wherein the forming the semiconductor layer is accomplished by solution coating using a dispersion including (a) a continuous phase comprising a solvent, a binder resin at least substantially dissolved in the solvent, and (b) a disperse phase comprising an organic semiconductor material, to form the semiconductor layer including the organic semiconductor material and the resin binder,
wherein the insulating layer, the gate electrode, the semiconductor layer, the source electrode, and the drain electrode are formed in any sequence as long as the gate electrode and the semiconductor layer both contact the insulating layer, and the source electrode and the drain electrode both contact the semiconductor layer.
The present invention is accomplished in additional embodiments by providing a field effect transistor comprising:
an insulating layer;
a gate electrode;
a semiconductor layer including an organic semiconductor material and a resin binder;
a source electrode; and
a drain electrode,
wherein the insulating layer, the gate electrode, the semiconductor layer, the source electrode, and the drain electrode are in any sequence as long as the gate electrode and the semiconductor layer both contact the insulating layer, and the source electrode and the drain electrode both contact the semiconductor layer.